BANGKOK, May 26 (Reuters) - The Thai military may have a well-rehearsed coup playbook after overthrowing a dozen governments, but it's never come up against the power of social media, as used by dissenters worldwide to share information - and that may prove a game-changer.

Since seizing control of the state on Thursday, Thailand's armed forces have arrested protest leaders, banned gatherings, gagged domestic media, blocked cable news networks and captured weapons from militant opposition groups. But they are struggling to deal with protests in cities that are erupting more like flash mobs than political rallies.

Protesters appear in droves only to melt away when soldiers link hands to encircle them. And when troops pick off and detain more vocal demonstrators, the others swiftly disperse and regroup elsewhere.

In uprisings as different in origin and outcome as the so-called Arab Spring and the London riots in 2011, the tech-savvy have harnessed social media platforms such as microblogging site Twitter to arrange rally points, share police or military positions and let others know about workarounds should authorities, as in Turkey, attempt to block the online chatter.

Protesters say they are keeping numbers low and gatherings scattered, to avoid presenting an easy target for any violent response. The protests appear to be stretching the army.

"We will do these small demonstrations every day until the coup is over," said one man at a protest on Sunday, who declined to be identified. "The people are not afraid any more. We will keep fighting."

The military has banned political gatherings of more than five people. "We would like to ask all people to avoid gathering to stage protests because it's not a usual situation for the democratic process," deputy army spokesman Winthai Suvaree said in a televised statement on Sunday.

SHAKING THE ROOTS

Protesters remain defiant. What began as a small group gathered outside a central Bangkok shopping mall on Sunday and swelled to several hundred after a lengthy and intense stand-off with the military that had huge play on Twitter.

It was difficult to calculate the size of the crowd because it was unclear who was protesting and who was simply watching, said a Reuters reporter at the scene. When authorities closed the public transport system stations at the nearest stop, word quickly spread on social media. Eventually, the troops withdrew, followed by a baying crowd.

Most gatherings have been held outside malls and mass transit intersections - drawing in onlookers and passers-by and again making it hard for soldiers to crack down.

"We'll have 100-200 people at different places," said one man, who didn't want to be named, at a Bangkok protest on Saturday. "This way, if we keep the numbers small, the army won't do anything. We'll shake the roots until the tree is uplifted and falls to the ground."

Groups have protested in the capital, in the northern city of Chiang Mai and, according to media, in Khon Khaen in the northeast.

In contrast, the military's use of media has been old fashioned, with an army spokesman reading out statements on TV from a plain desk against a white background, in a scene reminiscent of military coups in Latin America in the 1960s and 1970s. The camera switches to focus on a printed copy of the proclamation each time a statement is made.

Three days after the coup, the junta's National Council for Peace and Command (NCPO) still has no website. (Additional reporting by Martin Petty and Khettiya Jittapong; Editing by Sarah Edmonds and Ian Geoghegan)

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